The growth in consumer electronic appliances, of recent years, has led to a corresponding growth in devices for controlling such appliances. Controls are not only located on the appliances themselves, but also on remote units associated with the appliance. It would not be surprising to find more than a dozen control devices within the same house--each one operating in a slightly different manner, and each one having switches numbered 0 through 9. Indeed, one might even be inclined to speculate that the urge among humans to control distant objects by operating switches numbered 0 through 9 is a distinguishing characteristic of our species. Nevertheless, the proliferation of control devices continues at an accelerated pace; and so it is desirable to minimize the need for additional control devices, and to make future control devices more flexible.
In known systems where it is desired to selectively control a number of different appliances, it has been necessary to provide a separate control device for each appliances. Each of the appliances receives control signals over a direct link--at least one wire for each function being controlled. This proliferation of wires is remedied by U.S. Pat. No. 4,152,696 which teaches how a multifunction appliance can be controlled by transmitting different DC voltages. A simple, voltage-sensing circuit at the appliance would then activate a particular control line in accordance with the particular DC voltage transmitted. This technique decreases the number of wires needed for controlling a multifunction appliance without complex message signaling; but still requires separate wiring between the control device and the appliance which ties the control device to a fixed location. Further, a specialized control device is generally costly and becomes obsolete, or redundant, when the need arises to control additional appliances.
A system that combines a television receiver with a telephone interface is shown in U.S. Pat. Nos. 4,349,701 and 4,456,925. These patents disclose a 2-way telephone communication system which operates through a television receiver. The television receiver is interconnected with a telephone line and functions as a speakerphone. The user is provided with a remote control device which operates the television receiver and enables telephone calls to be answered or initiated. The switches on the remote control device are used to select a particular television channel or to dial a telephone number depending on which specifically defined task is selected.
A number of manufacturers even offer remote control devices that are capable of controlling a large number of appliances including television sets, compact disc players, stereo receivers and video cassette recorders (VCRs). Such control devices use infra-red light to transmit their control signals and offer the advantage that individual wires are not needed. Portability is achieved by eliminating hard-wire connections, but users don't understand how to operate more than a few control functions. Indeed, modern consumers now have so many bewildering conveniences at their fingertips that they are unable to use any of them.
Accordingly, there is a "long-felt" need to control a number of appliances from different locations within the home, and in a manner that the consumer can readily understand. Further, it is desirable for different control devices to operate in substantially the same manner. And finally, the ability to add remotely controlled appliances to a household, without a corresponding addition of remote control devices, would be most welcome.